Report for the Follow-Up Study
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Health and Safety Executive A further study of cancer among the current and former employees of National Semiconductor (UK) Ltd., Greenock 20030.01 cover final.indd 1 8/16/10 4:17:07 PM A further study of cancer among the current and former employees of National Semiconductor (UK) Ltd., Greenock Health and Safety Executive and Institute of Occupational Medicine United Kingdom Andrew Darnton1, Sam Wilkinson1, Brian Miller2, Laura MacCalman2, Karen Galea2, Amy Shafrir2, John Cherrie2, Damien McElvenny3, John Osman1 1Health and Safety Executive Epidemiology Unit Redgrave Court Merton Road Bootle Merseyside L20 7HS 2Institute of Occupational Medicine Research Avenue North Riccarton Edinburgh EH14 4AP 3University of Central Lancashire School of Public Health and Clinical Sciences Preston Lancashire PR1 2HE © Crown copyright 2010 First published 2010 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise) without the prior written permission of the copyright owner. Applications for reproduction should be made in writing to: The Office of Public Sector Information, Information Policy Team, Kew, Richmond, Surrey TW9 4DU or e-mail: [email protected] ii ACKNOWLEDGEMENTS Current and former management and workers at NSUK Greenock without whom this investigation could not have been completed, especially Susan Seutter, Bob Steel, and Douglas Blackwood. Steering Committee Members, Raymond Agius, Freda Alexander and Oliver Blatchford. Dr Rod Muir, former chair of the Privacy Advisory Committee, NHS National Services, Scotland. Staff at NHS National Services, Scotland, Information and Statistics Division (ISD), especially Roger Black, David Brewster, Laura Kelso, Susan Frame, Judith Stark, Richard Dobbie, Lesley Bhatti, David Clark, Douglas Clark, Susan Jensen, and Catherine Storey. Staff at the National Health Service Central Registers in Dumfries and Southport, especially Carolyn Macpherson, Muriel Douglas, Gail Turner, Patricia Bell, and Rhona Fraser. Staff at the Practitioners Services Division in Glasgow, especially Janet Mair, Lesley Taylor and Wendy Black. Local GPs and in particular, Dr Jim Ward. Brenda Bannister (Occupational Health Nurse Practitioner), who carried out interviews on behalf of IOM. Many others in HSE, IOM and elsewhere who have provided advice and support. All those who participated in the study including those contributing to the Historical Hygiene Assessment. iii CONTENTS Executive Summary ........................................................................................ vi 1. Introduction............................................................................................. 2 1.1 Background to the study ............................................................................... 2 2 Updated Cohort Analysis – Methods and Results .................................. 4 2.1 Methods........................................................................................................... 4 2.2 Statistical methods ........................................................................................ 5 2.3 Results ............................................................................................................ 7 3 Historical Hygiene Assessment ............................................................. 23 3.1 Introduction .................................................................................................. 23 3.2 Documentary records .................................................................................. 23 3.3 Interviews with long-serving employees ................................................... 23 4 Case-control and case-only survey – Method and Results.................. 25 4.1 Eligibility of Cases for the Case-control and Case-only studies ............. 25 4.2 Eligibility for Controls.................................................................................. 25 4.3 Sampling methodology for controls........................................................... 25 4.4 The recruitment process ............................................................................. 26 4.5 Interviews...................................................................................................... 29 4.6 Data processing ........................................................................................... 31 4.7 Exposure assessment ................................................................................. 33 4.8 Development of Exposure Matrices ........................................................... 34 4.9 Exposure assignment .................................................................................. 37 4.10 Statistical analysis.................................................................................... 40 4.11 Results....................................................................................................... 41 4.12 False Proxies: Recruitment ..................................................................... 74 5 Discussion................................................................................................ 80 5.1 Background .................................................................................................. 80 5.2 Findings ........................................................................................................ 81 5.3 Strengths and weakness of the study........................................................ 86 5.4 Interpretation of findings in the context of other studies ........................ 89 6 CONCLUSIONS ........................................................................................ 91 7 References ............................................................................................... 92 iv Appendix 1 – additional Results Tables and charts.................................... 95 Appendix 2 – Worker Information Leaflet................................................... 115 Appendix 3 – Adjusting the cohort mortality and cancer incidence analysis for deprivation: methodology and comparison of results ......... 117 Appendix 4 – Job Exposure Matrix (JEM) .................................................. 121 Supplementary web material (Available at UUhttp://www.hse.gov.uk/statistics/nsuk/repapp2010.pdf) Appendix 5 – Questionnaires and Flashcards Used Appendix 6 - Letters of invitation to take part in the study v EXECUTIVE SUMMARY INTRODUCTION This report by a joint research team from Health and Safety Executive (HSE) and the Institute of Occupational Medicine (IOM) describes the results of a study carried out in response to the findings of an earlier investigation into concerns about cancer at National Semiconductor (UK) Ltd (NSUK). That investigation could not exclude the possibility that work at NSUK may have contributed to the higher than expected incidence of certain cancers, and particularly lung cancer, in the workforce. It recommended further research to follow up those findings and prompted the investigation reported here. The aim of this study was to assess the whether workplace exposures contributed to any increased risk of these cancers by carrying out: 1. an update of the original cohort analysis of overall mortality and cancer incidence among this workforce; 2. a plant-based case-control study of lung cancer and breast cancer in which the work and lifestyle histories of cases and a sample of NSUK workers without these cancers would be compared; 3. an examination of the work and lifestyle histories of the smaller number of cases of female stomach and male brain cancer. The protocol for the study was approved by the appropriate local NHS Research Ethics Committee and Research and Development function, and by the Privacy Advisory Committee for the NHS National Services, Scotland, Information and Statistics Division (ISD), and General Register Office for Scotland (GROS). During the course of the study the protocol was amended to restrict the lung cancer analysis to an examination of the work and lifestyle histories of cases only rather than a full case-control analysis because of the low response rate amongst the cases. This change was agreed with the local research ethics committee and the NSUK workforce was informed. METHODS The updated cohort analysis was carried out using same methodology as in the original study. Deaths and cancer registrations among the workforce were obtained in order to calculate Standardised Mortality Ratios (SMRs) and Standardised Cancer Registration Ratios (SRRs) for a predefined set of disease groups using reference rates based on Scottish national mortality and cancer registration data. We examined the same disease groups as in the original analysis with the addition of brain, central nervous system and ovarian cancer. Since NSUK workers were drawn from an area with higher than average levels of deprivation, we adjusted SMRs and SRRs to allow for associations between these diseases and deprivation. An Historical Hygiene Assessment (HHA) was undertaken to gather information about processes, working practices and working conditions at the NSUK plant since it opened. Documentary evidence from NSUK and HSE inspections was reviewed and supplemented by information from interviews of long serving NSUK employees nominated by NSUK and Phase Two, a local support group for workers at the plant. This assessment was used to develop a job exposure matrix that linked jobs done at NSUK to